1. Field of the Invention
The present invention relates to an optical waveguide device for a touch panel, and a production method for the optical waveguide device.
2. Description of the Related Art
Touch panels are input devices for operating an apparatus by directly touching a display screen of a liquid crystal display device or the like by a finger, a special stylus or the like, and include a display which displays operation items, and detection means which detects the position (coordinates) of a portion of the display screen of the display touched by the finger or the like. Information of the touch position detected by the detection means is sent in the form of a signal to the apparatus, which in turn performs an operation specified by the touch position. Examples of the apparatus employing such a touch panel include ATMs in banking facilities, ticket venders in stations and portable game machines.
A detection device employing an optical waveguide is proposed as the detection means for detecting the finger touch position on the touch panel (see, for example, US2006/0002655A1). As shown in FIG. 10, the touch panel includes an elongated optical waveguide 70 wrapped around the periphery of a rectangular display 31. The optical waveguide 70 includes a multiplicity of cores 73 including light emitting cores and light receiving cores through which light passes. The light emitting cores and the light receiving cores are respectively located on diagonally opposite sides of the display 31. Light emitting means 12 such as a light source is connected to proximal ends of the light emitting cores 73 at one end of the elongated optical waveguide 70, and light receiving means 13 such as a light detector is connected to proximal ends of the light receiving cores 73 at the other end of the optical waveguide. Distal end faces (light emitting surfaces) of the light emitting cores 73 and distal end faces (light incident surfaces) of the light receiving cores 73 are positioned on one longitudinal side edge of the elongated optical waveguide 70, and oriented in the same direction as the display screen of the display 31 with the optical waveguide 70 being wrapped around the periphery of the display 31. Light from the light emitting means 12 passes through the light emitting cores 73, and is outputted in the form of multiple light beams from the distal end faces (light emitting surfaces) of the light emitting cores 73 in the same direction as the orientation of the display screen of the display 31. Then, the light beams are deflected in a direction parallel to the display screen of the display 31 by a rectangular frame lens (not shown) provided on upper edges of the display screen of the display 31. Further, the light beams are deflected by an opposed frame lens portion and inputted to the distal end faces (light incident surfaces) of the light receiving cores 73. Thus, the light beams travel in a lattice form on the display screen of the display 31. When a portion of the display screen of the display is touched by a finger in this state, the finger blocks some of the light beams. Therefore, the position of the screen portion touched by the finger is detected by detecting a light blocked portion by the light receiving means 13 connected to the light receiving cores 73 of the optical waveguide 70. In FIG. 10, reference characters 72 and 74 denote an under-cladding layer and an over-cladding layer, respectively.
In the case of the touch panel employing the aforementioned optical waveguide 70, the light emitting cores 73 should be aligned with the light emitting means 12 (for optical axis alignment) so that the light from the light emitting means 12 can be inputted to the light emitting cores 73 at the one end of the optical waveguide 70 wrapped around the periphery of the display 31. Further, the light receiving cores 73 should be aligned with the light receiving means 13 (for optical axis alignment) so that the light receiving means 13 can receive the light outputted from the light receiving cores 73 at the other end of the optical waveguide 70. An accurate alignment operation is troublesome with the need for precision, thereby requiring efforts and time.